Today's Wonder of the Day is about a phenomenon that we've all experienced from time to time. Remember the last time you went sledding?

It was probably pretty cold outside, wasn't it? But when the wind would start to blow, it would suddenly feel much colder.

Why is that? Is it magic? Nope! It's just science. Meteorologists call this phenomenon the wind chill factor.

Wind chill is what the air temperature feels like on our exposed skin due to wind. It's always lower than the actual air temperature.

For example, even though the thermometer may indicate it's 35° F (1.6° C) outside, a 25-mile-per-hour wind will make it feel like it's only 8° F (-13.3° C)!

The opposite effect can occur at temperatures above 50° F (10° C). At higher temperatures, humidity on the skin can make the air temperature feel hotter than the actual temperature. Meteorologists call this effect the heat index.

It's important to note that wind chill is a prediction of what experts believe humans will perceive the temperature to be because of the wind. No matter how fast the wind blows, the air temperature is what it is and can be measured by a thermometer.

The wind chill factor, on the other hand, is calculated using various formulas. There is no one formula that all scientists agree on. Most meteorologists in the United States use a standardformula accepted by the National Weather Service.

What causes the wind chill effect? It's a result of the fact that the human body loses heat through a scientific process called convection.

During convection, heated air molecules rise into the air and are replaced by cooler air molecules. How quickly your body loses heat by convection depends on air flow around your body.

Your warm body usually loses heat slowly. When it's windy, though, the wind carries the warm air molecules away from your body more quickly, making you feel colder than the actual air temperature around you.

The faster the wind blows, the faster your body loses heat by convection. As the air temperature around you falls, the effect of wind is magnified, making the wind chill effect greater the colder it gets.

If you've ever blown on a hot bowl of soup to cool it down before eating, you've created your own wind chill effect on your soup!

Even though the air temperature stays the same, the presence of wind makes us feel like it's colder outside than it actually is. The wind chill effect isn't all mental, though.

Since wind chill speeds up heat loss by convection, our bodies experience heat loss and react as if the temperature were as low as it feels…even if the actual air temperature is much higher than the wind chill factor.

Wind chill factors are calculated under the assumption that a person is properly dressed and dry. If you're not wearing suitable outdoor clothing, if your clothes are wet, or if you've been outside for an extended period of time, the wind chill factor will be magnified even further.

Did you get it?

Wonder What's Next?

Tomorrow’s bubbly Wonder of the Day will get you squeaky clean!

Try It Out

Are you ready to chill out? Be sure to explore the following activities with a friend or family member:

Ready to estimate and calculate wind chill? If it's cold where you live, grab a thermometer and head outside. What is the actual temperature right now? Is it windy? Does it feel colder than the actual temperature because of the wind? Make your best guess about what the wind chill factor might be. Then head back inside, grab the computer, and go online to check out this cool (pun totally intended) wind chill factor calculator! Just plug in the actual temperature and the estimated wind speed to learn what the wind chill factor is. Was your guess close? Try plugging various numbers into the calculator to get a sense of what wind speeds drop the temperature by how much.

Want to conduct a simple science experiment with hand sanitizer to learn more about the process of evaporation and how it simulates wind chill? Check out Create Evaporation online to learn more. Be sure to share what you learn with a friend or family member.

To learn more about the opposite of wind chill, otherwise known as the heat index, check out this online Heat Index Calculator. Which do you think is easier to deal with: wind chill or heat index? Why?

Wonderopolis

ali

Wonderopolis

Dec 23, 2011

Hi, Ali! Thanks for stopping by this Wonder of the Day® and leaving us a comment! We DO have some Wonders about football! Here they are with links that will take you right to them:
Wonder #336 – Are Footballs Really Made Of Pigskin? https://www.wonderopolis.org/wonder/are-footballs-really-made-of-pigskin/
Wonder #126 – What’s So Super About Super Bowl Sunday? https://www.wonderopolis.org/wonder/what-s-so-super-about-super-bowl-sunday/
We don't yet have a Wonder about Ohio specifically, but we thought it might be fun to share two Wonders with you that say something about Ohio in them! See if you can find the Ohio references in these Wonders:
Wonder #61 - Who Invented Cotton Candy? https://www.wonderopolis.org/wonder/who-invented-cotton-candy/
Wonder #12 - Who Came Up With Chewing Gum? https://www.wonderopolis.org/wonder/chewing-gum-101/
Happy WONDERing! :-)

Joey

Wonderopolis

Dec 22, 2011

We think a Wonder about llamas would be AWESOME, Joey! Did you know there are already some Wonders about baseball? Check these out:
Wonder #289 - How Fast Is a Fastball? https://www.wonderopolis.org/wonder/how-fast-is-a-fastball/
Wonder #155 - What Is Spring Training? https://www.wonderopolis.org/wonder/what-is-spring-training/
Thanks for leaving us a great comment today! :-)

5A in Gibbons!

Dec 22, 2011

That wonder sent a chill up my spine! Here in Gibbons it's blowing like there's no tomorrow!
That video was very random, though...
You guys should watch "10 reasons not to come to Australia"... it's our favorite video on youtube! :)

rainvbe

Dec 22, 2011

Ever wondered if the fact that we have heat surrounding us is a heat factor, and the wind is making us feel the real sensation of the temperature? Like 25F feels more like 27F without wind nor too much humidity, and the chill effect brings us the sensation of a real 25F?